Induction-motor.



A. M. GRAY.

INDUCTION mo'ron.

APPLICATION FILED FEB. 28, 1910.

Patented Jam 7, 1913.

UNI ED STADESQPATENT onnion.

In men COMP 1 5 i i Toall whomc't may concern ,B-itigknown that L ALEXANQER M. GRAY a'subjectof the :King of England, residing at -Milwau'ke 5 and-State of tain new and usef duct-ionlMotorsof W full, clear and exact specification. -My inyention relates to dynamo electric machines, and particularly to induction moisconsin, have invented cer- Improvements m. In-

' It is desjir'able fonthe running condiQ lions ofinductfion motors that-theresistance iof-"the' closed secondaryv windings. be very 15 loan; The low resistance is notadvantageons, however, for u starting,; owing to the fact that the currents induced in the secondary :winiiings are'soc-large-that they react-Z upon the field; andgreatly qveaken the-semis gi -r 2.0, a eg-1 'ngtorque. It a res st:- ance "erted in the secondary windings; upon starting, the strength off'the "currents iscorrespondingly reducedand gfreater effective starting torque obtained, -25 t-is,therefore, common to insert resists cecircuit with thensecondaryiwindings on starting and tocut this resistance out ,when

the motor has come up to: speed. In this malmeu the requirements of. best; starting 80 -and running conditions are fulfilled.

1 The ob'ect of my invention is to provide fasimple andiefiective arrangement of parts,

and easilyc/ontlolled means for inserting refi slstance In the circuit of the secondary or 36 rotor windings upon start'ng and for shortcircuiting'the windings a ter the motor has.

attained a predetermined speed.

- My invention consists in certain novel de ta ils of-construction and combinations and 5i) Mounted upon t e sha jrtrlt) oi a'dj namo electric machine is a spider 12 carrying a core 13," preferably laminated and-providedv V Speinficetionof;Lettersiliatenh Application filed February-23, 1am. Serial No. 546,543.

'"= the county oatMilwaHkee' ch theiollowing is anm'th t endye ing' position, the [wishes to 9B. FEW JERSEY- Patented qanjmieis.

with the usual slots, which i ecei've win. or windings 14, the ends of whiclrproject beyond the ends :\of the core.'-; The shafit 10 rotates in a bearing which is mount a bearinghousing 15. whichis support by a, pedestal 16. Surrounding a portion oi the bearin housing 15, secured thereto;-and-insula. therefrom are: threefstaltionary slip rings 17 which are:- insulateda-from'each. other. These slipzrings-are .to van external a able resistwc reto between the housing l5 laznd is ider l 2;-is a hearumm ng m er .ls arms 19 and 2Qwhich, surroundsfithe slip, 17;, the ring. QQibeirIgcOncent-ricinIy;

Studs 21 are riveted to these arms; and support sleeves 22 each, ofj.--which ;has.-a long projection 23 and one'slee-irea shorter. projection 2A. At the extreme 'end of each ofv the. long, projections pin 25' which i ada 'ed to slide in a=ggrooved portion 26. iii, ,eac of arms 27 mounted on a hub 28 which is'loosel'y fitted and is free to move Qll Qlle shaft 10 bet ween Mite short-circtiit-ing. member 18 and bearinghousing, 15, Ba ofthe sleeves 22 is further {providedwith a.

long arm- 29 provided at its'end'with anjen- 'larged. portion which is adapted to receive a,

brush 30, These brushes] are; connected b Mounted connectors 31 to the rotor orts'ccondary wind ings. of the induction motor.,,"'1he brushes are spring-pressed, and in their-normal positions are held in engagementwwithI'theslip rings 17 and are locked in suclrposit-ion by a centrifugally operated device consisting of a latch 32 engaging the small projection 24, as shown in Fig. 2, and hayin g'gat (mound a weight 33. The latch is held niiposition' locking the brushes 30 in engagement with the slip rings 17 by a spring 34, one end of which is secured to the latch and the other end'to a portion of the short-circniting member 18.-

The weight 33 may he shiftedi iii either direction on the latch 32, depeiidhrgmpon the speed atwhich .i t is \l:ll8d to change the connections of the windings'relafif to the slip rings and shortanointingrings.

Vhn the motor is at menu" secondary windings are connected engage "the slip rings 17 which are connected to the external resistance 37. As the motor is speeded up the resistance 37 is cut out of circuit gradually and the weightgradually moves away from the center of rotation, due -to the action of centrifugal force,"

and moves the other end of the pivoted latch in a direction ,to disengage the small projection 24. At .a-jcertain predetermined speed the weight flies out to' its extreme position, lowering thela-tch, the brushes 30 a snap out of engagement with the slip rings nection with the short circuitin ri and into engagement-with the short-circuitthe brushes 30 remain contact with the hort-circuiting ringieigg necessary for the rotor to run at' its m so.

mum speed or nearly the machine is being stopped, centrifugal force will be overcome by the-action of the springs 36 and the brushes wilggireaj cons and beiiconnected again with tne'lsli rings." At thislfpoint the weight 33, 1 move foward th'e'center of rotation and the latch willagain engage the small projection 2 1, lockinglthe brushes in their normal position, Which is in .engagementvwith the slip rings. By means of the arran ement disclosed in this specification and A rawings, simple,

effective and desirable operation of inductionlm otors of the rotor wound type is attained":

There may be many modifications of the precise arrangement here shown and described and I aim in my claims to cover all such modifications which do not involve a departure from the spirit and scopeof my invention.

What I claim as new is 1. In an induction motor, a stationary slip ring. a secondary winding electrically connected to said slip ring, a short-circuiting 'rin surrounding said slip ring, and' means f or disconnecting the electrical connections of said secondary winding with said slip ring and for connecting said winding with said shortcircuiting .ring.

2. Ina dynamo-electric machine, the combination of a stationary slip ring, a shortcircuiting ring, said rings being oo ncentri cally arranged, a winding adapted to be connected to either said slip ring or to said short-circuiting ring, andmeans for making and breaking said connections;

thesecondary winding. or wind- P If at any time the rotor speed .falls off an appreciable amount, as for instancewhen 3. In adynamo-ele'c'tricmachine, the combination of a stationary-slip ring, a shortcircuiting ring surroundingsaid slip ring, a winding adapted to be'electrically connected to either said slip ring or short-circuiting ring, and centrifugally operated a mit the moving ofsa-id brush for changing the connections of said winding from said slip ring to said short-circuiting ring.

5. In an induction motor, a stationary slip-ring, a secondary winding electrically Y connected to said slip' ring, a revolving short 1 circuiting ring surrounding said slip ring,

I and meansfor disconnecting the electrical connections of said secondary winding with said slip ring and for connecting said windingw-ith said short-circuiting ring. a

6. In an induction motor, the combination of a stationary slip ring, a revolving shortcircuiting ring arranged concentrically with respect to said slip ring, a windingadapted to beelectrically connected to either'said slip ring-or short-circuiting ring, ,and centrifugally operated means for making and breaking said connections.

7. In an induction motor, the combination of a slip ring, a variable resistance connected to.said slip ring, a movable shortcircuiting ring. surrounding said slip ring, a winding adapted to be electrically connected to either said slip ring or shortcircuiting ring, and means which when operated permit the making and breaking of said connections.

8. In an induction motor, the combination of a rotatably mounted-winding, abrush, a centrifugally operated arm in which said brush is mounted, a slip ring to which said winding is. normally connected through said brush, a short-circuiting ring to which said winding is adapted to be connected,acentrifugally operated latch having an adjustable weight thereon, said latch being associated with said brush arm for-retaining the electrical connection between said winding and' slip ring, and a" spring for restraining said weighted latch against centrifugal action up to a predetermined value at which time said brush and winding will be disconnected from said slip ring and connected to said short-circuiting ring.

9. In-an induction motor, the combination of a rotatably mounted winding, a stationary slip ring to which said winding is connected,

a rotatably mounted short-circniting ring surrounding; said slip ring and to which said winding is adapted to be connected, and

centrifugaiiy operated means for disconnect- 5 ing said winding and slip ring and con-" Witnesses:

meeting said Winding and said short-circuit- CHAS. LBYRON,

ing ring. Ron. E. STOLL.

Mihvaukee, \Vis. Feb. 23, 1910. In testimony whereof aflix my signature, in the presence of two witnesses.

ALEXANDER M. GRAY. 

